LED Chip Sidewall Dicing for Uniform Light Module Mounting

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Solution Overview

Problem

Conventional light emitting diode (LED) wafer dicing processes result in inclined side surfaces, leading to chip rotation and irregular mounting during transfer, causing beam angle irregularities and reduced light uniformity in light emitting modules.

Innovation Solution

A light emitting module design with modified laser-irradiated regions and ruptured regions on the substrate, where the first and second side surfaces are cut at specific angles to create perpendicular surfaces, preventing chip rotation and ensuring uniform luminance by using femto-second laser processing for precise cutting and minimizing thermal damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional laser dicing is used to cut the wafer, then the dicing process is simple and fast, but the side surfaces of the chips become inclined, causing chip rotation and irregular mounting

Engineering Contradiction:

Improveside surface perpendicularityVSAvoiddicing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The dicing process is segmented into multiple stages: first creating modified regions with laser irradiation, then forming ruptured regions through mechanical stress, and finally separating the chips. This segmentation allows the side surfaces to be cut perpendicular to the top surface while maintaining process efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Laser irradiation is applied in advance to create modified regions within the wafer before the actual cutting occurs. These pre-modified regions serve as stress concentration points that guide the subsequent mechanical rupture to form perpendicular side surfaces, eliminating the need for complex post-processing.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If chips with inclined side surfaces are transferred, then the transfer process is fast, but the chips rotate and fall down on the circuit substrate

Engineering Contradiction:

Improvechip mounting stabilityVSAvoidchip transfer speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The invention applies preliminary anti-action by creating perpendicular side surfaces through controlled laser modification and mechanical rupture before transfer. This pre-established geometric stability prevents chip rotation and falling during the transfer process, eliminating the need for slow, careful handling.

Inventive Principle:

Principle #9Preliminary anti-action

3Manufacturing precision

If conventional dicing is used, then the production speed is high, but the mounted chips have irregular beam angles and reduced light uniformity

Engineering Contradiction:

Improvebeam angle consistencyVSAvoiddicing speed

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the physical parameters of the wafer material through laser irradiation, creating modified regions with different mechanical properties. This parameter change enables controlled rupture along perpendicular paths, ensuring consistent beam angles while maintaining high dicing speed.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution ensures that light emitting chips are mounted without rotation, maintaining uniform luminance and improving light extraction efficiency, preventing chip fall and ensuring consistent light emission through the side surfaces.

Implementation Method 1

modified regions MDF are formed by concentrating and emitting a laser beam to a predetermined depth of the wafer

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

The wafer is ruptured based on the modified regions

Methodology Applied

Scientific EffectPhotoelasticity: Photoelasticity

Data Source

PatentUS11923345B2Light emitting device and light emitting module including the same

Publication Date: 2024.03.05 SEOUL VIOSYS CO LTD

AI summary

A light emitting module including a mounting substrate, light emitting chips mounted on the mounting substrate, and pads, in which the light emitting chips include a first substrate, a first light emitting unit on a first surface of the first substrate, a second substrate spaced apart from the first substrate, and a second light emitting unit on a second surface of the second substrate, the first substrate includes a first side surface including a first modified surface, and the second substrate includes a second side surface facing the first side surface and including a second modified surface, the first modified surface includes first modified regions extended in a thickness direction and first ruptured regions disposed therebetween, the second modified surface includes second modified regions extended in the thickness direction and second ruptured regions disposed therebetween, and the first ruptured regions have the same width as the second ruptured regions.